This is a simple code to add a form in a page:
add_shortcode( 'myform', 'add_myform' );
function add_myform( $atts ) {
if ( isset( $_POST['myname'] ) ) {
$myname = $_POST['myname'];
update_option( 'myname', $myname );
} else {
$myname = get_option( 'myname' );
}
$myform = "<form method='post' action=''>";
$myform .= "<input type="text" name="myname" value="" . $myname . "">";
$myform .= "<input type="submit" value="Submit">";
$myform .= "</form>";
return $myform;
}
Add the shortcode [myform]
in a page and the form will be shown.